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Chapter 4 Cell Structure & Function

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Cells
The basic units of structure and function in all organisms.
Hooke
Named cells after viewing dead empty cork cells- reminded him of monk rooms, also called cells.
Leeuwenhoek
First to observe and record data on living cells.
Schleidon
A Botanist concluded that all plants were composed of cells.
Schwann
A zoologist concluded that all animals were composed of cells.
Virchow
A physician who observed ell division
Cell Theory
The work of these individuals and others were combined into this theory. 1. cells are the basic units of structure and function in all organisms. 2. all organisms are composed of 1 or more cells. 3. Cells come from pre-existing cells through cell division
Virchows Principle
Principle that says that cells come from preexisting cells through the orderly process of cell division.
Cell size
Cells average from 10-50 microns in diameter, they are limited to this size due to their surface area to volume ratio
Surface area
The cells amount of cell membrane. cells obtain all their needs by absorbing them across their cell membrane
Volume
the amount of cellular contents.
Cells Increase in Size
a cells amount of cell membrane (their surface area) increases by the square but their volume increases by the cube. with increased volume the cell has a greater demand for food, oxygen, and produces more waste but its cell membrane (surface area) its to small to handle these increased demands.
Cell Structure or Shape
varies with function ex: Red blood cells are spherical to move through capillaries with least amount of friction. certain types of white blood cells can change their shape to surround and engulf foreign bacteria.
Types of Cells
Prokaryotic and Eukaryotic.
Prokaryotic
cells that lack an organized nucleus and lack membrane- bound organelles.
Membrane- Bound Organelles
a cell part that is covered by a membrane ex. Bacteria.
Eukaryotic
have an organized nucleus and membrane, bound organelles ex. all cells except bacteria
3 major regions of eukaryotic cells
Cell or plasma membrane, cytoplasm, and nucleus
Cell or plasma membrane
separates cells from external environment. It is said to be semi or selectively permeable. the cell membrane is composed of a lipidbilayer with proteins and carbohydrates all with a significant function.
Semi or selectively permeable
it is able to regulate what may enter and exit cell.
Lipidbilayer
2 layers of phospholipids
Water loving lipids orientation
they are orientated so that their polar hydrophilic components are adjacent to aqueous environments.
Aqueous environments
The inner and outer surface of a cell membrane
Hydrophobic lipids
the non-plar, water fearing hydrocarbon chains are positioned away from water, towards the center of cell membrane.
Proteins in lipids
they act as attachment sites for molecules in the extra cellular fluid and they form channels to transport substances in and out of fells
The position of the lipids, proteins, and carbs
they constantly change due to changes in cellular demands throughout the course of each day. because of this ever-changing patterns of organic components in the cell membrane, it is referred to as fluid mosaic model
Fluid Mosaic Model
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.
Cytoplasm
The second major region of cells. contains a jelly-like fluid called the cytosol
Cytosol
suspends the organelles
Organelles
the functioning structures in cells
Ribosomes
most numerous of all organelles, unlike most other organelles are not membrane-bound. Their main function is to organize protein synthesis (building)
Endoplasmic Reticulum (E.R.)
folded sacs and tunnels found throughout the cell. Prepares proteins for export and synthesizes steroids
Golgi Apparatus
processes and packages substances produced by the cell. ex. Lysosomes are packaged by the golgi apparatus
Lysosomes
packages of digestive enzymes that digest food molecules and recycle worn-out cell pars, found only in animal cells. Functionally similar to the vacuoles found in plant cells
Mitochondria
carry out cellular respiration- the chemical breakdown of glucose to provide useable energy in the form of ATP which is used to power all cellular activity. These organelles are most numerous in cells with high energy requirements such as muscle cells.
Microtubules and microfilaments
protein rods that shape and support cells forming the cytoskeleton.
Nucleus
stores DNA and synthesizes RNA. Surrounded by a double walled membrane called the nuclear envelope through which substances may enter and exit via nuclear pores. Contains one or more circular organelles called nucleoli which function to synthesize ribosomes.
Nucleoli
circular organelles which function to synthesize ribosomes
Cell Wall
plants. found in addition to a cell membrane, cell wall is outermost covering. Composed primarily of polysaccharides Cellulose
What a cell wall does
... functions to support and protect a cell.
Vacuoles
store water, wastes, enzymes, toxins. they are functionally similar to lysosomes in animal cells.
Plastids
store photosynthesis pigments and other organic compounds.
Types of Plastids
chloroplasts and leucoplasts
Chloroplasts
store photosynthetic pigments called chlorophylls
Leucoplasts
store starches
Levels of Organization
cells make up tissues, tissues make up organs, organs make up organ systems, and organ systems make up multi cellular organism.
Tissues
cells of the same type working together to preform a function
Organ
2 or more different tissues working together to preform a function
Organ System
2 or more different organs
Colonial Organisms
a group of genetically identical cells that live in closely connected groups. Ex: bryozoans
Similarities between colonial organisms and unicellular beasties
Each individual is capable of living independently and do not have tissue and organs
Similarities beween colonial organisms and multicellular beasties
there composed of many cells and do exhibit some cell specialization
Cell specialization
Different cells are able to perform specific tasks
Scanner lens
smallest lens 4 or 5x.
Low Power Lens
10x lens
High Power Lens
40 - 50x lens
Stage
slide is placed there
Diaphragm
regulates light passing through slide
The cell membrane...
is composed mainly of a lipid bilayer
Endoplasmic reticulum (E.R.) and Golgi apparatus
Substances produced in a cell and exported outside of the cell would pass through the...
Mitochondria
cells that have a high energy requirement generally have many...
Lysosomes
Viruses, bacteria, and old organelles that a cell ingests are broken down in...
Nucleus, chloroplasts, and mitochondria
organelles that are surrounded by two membranes and contain DNA are the...
Cilia
short, hair-like structures made of microtubules that enable movement of cells or movement of materials outside a cell
Flagella
long, thin, whip-like structures, with a core of microtubules, that enable some cells to move
What regulates cell size? Why is this so important? What happens when it changes size?
Surface area to volume ratio; through surface area cell gets food and such; surface area to volume changes
Describe the composition, components, and orientation of organic compounds in region 1. Why is the cell membrane called a fluid mosaic model?
Composed of a lipid bilayer with proteins and carbs all with a specific function. Lipids are oriented so their polar, water- loving, hydrophyllic components are adjacent to aqueous environments. The nonpolar , water-fearing hydrocarbon chains are positioned away from water towards the center of the cell membrane. The proteins act as attachment sutes for molecules in the extracellular fluid + they form channels to transport substances in and out of cells; the position of lipids, proteins, and carbs constantly changes due to changes in cellular demands. This ever changing pattern makes it a fluid mosaic model.
Describe 2 differences between prokaryotic and eukaryotic cells. Examples
Prokaryotic cells lack an organized nucleus and membrane- bound organelles eukaryotic have these. Prokaryotic- bacteria. Eukaryotic- anything but bacteria
Rough E.R
has many ribosomes on its surface and is indicative of cells that synthesize numerous proteins for export
Smooth E.R
has few ribosomes on its surface